Chimney cap



Nov. 24, 1953 SABlN, JR 2,660,105

CHIMNEY CAP Filed May 11, 1949 2 Sheets-Sheet l ,(YYYYV'YV'Y'Y'VE Q: 0 .w noun 0 u; .E .Nz i)..............* 5.

NOV. 24, 1953 $AB|N, JR 2,660,105

CHIMNEY CAP Filed May 11, 1949 2 Sheets-Sheet 2 Patented Nov. 24, 1953 UNITED STATES PATENT OFFICE 7 CHIMNEY OAR i V a Harold A. Sabin, J r., Pjortland, Maine Application Mayvl l, 1949 Serial No. 92,611

1 "1 My present invention relates to; tion of chimneys and particularly to caps-therefor. 4

Many chimneys prove unsatisfactory in; use with their failure to function properly being most commonly attributable to inadequate drait due to improper design, the influence of dpwfn drafts, or spot, deposits and creosote formations. It is the primaryobjectiveof this invention to provide acaprthat maybe attached to .a chimney top toiensure adequate draityunder all circumstances and to maintain the chimney in goodcondition. In accordance with rmy invention, ,1 provide a chimney top consisting of a cap part extending upwardly from the upper, end of the chimney and having ports adjacent itslower end of such peripheral extent that air may flow through the shelltransversely or from end to end thereof. The upper end of the, chimne is closed by a plate through which extends a conduit with its upper portion housed by but spaced from the 4 car rs. (01 525351 the construe:

shell and with its upper endlbelow the upperend of thelshell but above itsports. Preferably, both theshell and the hollow member are of frustoconic form and a spark arrestorisattachedto the lower end of the hollow member.

.1. With such a, cap, the conduit provides a fine outlet of substantially lesser cross sectional area than that of the chimney interior andpref erably extends downwardly into the chimney toensure 1 that, there is a head of warm gas adjacent the cap. ,The space between theconduit and the cap part provides adownward p ss for d wn drafts while generally horizontal air currents passtransversely through the ports in the shell. These factors combinerto ensurethat a desired chimney draft exists that is essentially a thermal draft and that flue gases in the chimney are above the dew point thereby minimizing condensation, soot deposits, andcreosote formations with the flue or flues M p In the accompanying drawings, {have shown illustrative embodiments of my invention from which these and other of its novel features and advantages'will be" readily apparent. Q'I n the'drawin'gs': n Fig. lis a top plan view of the chimney.

Fig. 2 is a rragmntar viewym elevation, of a, completed chimney in accordance with inyinre i '5 f1 Fig; 3' is a'secti'on','6n' an enlarged scale, along the lines 3 '-3of Figl'2f I Fig.4 is a veruoars'ouoe through achimney showing a modification of my, invention.

Fig. is a vertical section showing another modif cation of my invention, and i 4 Fig. 6 is a viewyin :elevationfona reduced scale of he chimney shown inijFig', 5.?

i1 nfFigs. 1-3; I'ha've" indicated a omimie y lo mg "a fi ue '1 r whichj is off the conventional rect ng lar cr se t onal shap v 2 A mm the.- embodiment of my invention shown in the drawings, I- close the upper end of the chimney I0 with a plate l2 having downturned edges [3 =anda bottom flange [4 to enable it to be cemented as at IE to the top of the chimney l0. {line plate l2; centrally apertured to receive the conduit l5 and to support it preferablywith its lowergpart extending downwardlyjinto th'e .fiue Ll. Attached tdthe lower vend of the eonduit lfi is a sparlg arresting screen elementfl'l, preferablyinthe form of a basket. I have shown the conduitsupper end as protected by a hood l8.

At l9 I have indicated a cap part in theform 13a. shell xattachedrto' the plate [2 by spaced supports 20 of tubular stock so that air currents may, enter. or leave the shell 19 subtantially withoutlobstructionlfiandregardless of their direction. Whilethesupports may be otherwise anchored I have shown them as locked tolthfe plate I 2. 'Ifhe s hell [9 receives the upper part otthe conduit [6 within it with the upper endof the conduit l6 positioned below the upper enjd of the shell 19 but, above its ports defined by the supports: 20 andwith a substantial space between them. In practice both the conduit l6 and'the shell [9 are of frustro-conic section, i

Q While-the sh'ell'l9 may be, otherwise formed,

have shown it ias a metal casing 2| having ce- In unusual circum tances as with tall,

neys or thosein poor condition, an extension,

conveniently consisting of C tubular sections 24 may be connected to the lower end of the conduit I 6 assuggested in' Fig. 4. Such an extension isltof, sufficient, length to extend below the zone of vapor condensation thereby ensuring that flue gases ntrantlof the member, I6 are above the dew' q n 1 I Inc-Fig. 5 I vhaveshown an embodiment of my invention in whichjhecap part I9 is made from bricksso thata chimney, capped in accordance with my irive'ntion will be more conventional in appearance f,Where"the cap isthus made, it is provided with a plurality of ports 25 adjacent the plate 26. an'djhas itsjupper end closed bya plate nl tin e ppr't28 therein. V In practice I v have had good results with the juppe'r' endof the conduit l6 being approximately midway ot'lthe 6.5 of the shell l9 and with its 1 imum diameteri in theorder of one-half the avrage'of widthof adjacent sides of the ass-i i r 1- 311 team he She 19 p ,rably pne-half of the ,diagonal'of the insideof qthe -chimney and theglower portion of the conduit a 1-6 @is approximately one-half the; length ;.of;-,. its

r'rI have -foundthatest rams as obtained when 'thef area ofitheoupper end of the-shell l9 is- 'eqiial t'o thoupper end or the' conduit l6 but 3 that the space between the conduit 16 and the shell 19 may be varied appreciably.

With a chimney cap in accordance with my invention, the conduit It establishes a flue outlet of substantially less cross sectional area than that of the flue l I into which it extends and, as a consequence, flue gases, discharged therethrough, have an increased velocity.

Should the chimney [9 be so located and dimensioned that down drafts are common that would normally enter the flue H to disrupt the up draft therethrough, such currents follow the path of least resistance and flow downwardly be-. tween the conduit l9 and the shell I9 and escape between the shell !9 and the plate 12. In this, a contributing factor is that such down drafts tend to create an assisting suction at the base of the shell 19. While the use of a hood is for the conduit 16 prevents moisture from entering the flue H, chimney caps in accordance with my invention minimize the effects of precipitation without such a hood as any precipitation entering the conduit 18 is directed thereby to pass downwardly into the flue without touching its walls, While such precipitation is not a serious factor when the chimney is heated, it contributes, in a cold chimney, to the deterioration of the cement.

In this connection, it will be noted that where the lower end of the conduit 16 extends below the plate l2, a head of warm gas is maintained at the upper end of the chimney in the zone 29. In addition, my caps prevent relatively cool outside air from entering the flue with the result that even during severe winter weather, the flue gases normally remain above the dew point so that condensation is held to a minimum. Condensation is objectionable in that it causes carbon to adhere to the walls oi the chimney and creates liquid creosote.

From the foregoing, it will be apparent that chimney caps, in accordance with my invention, are of simple construction and, particularly when made in the proportions which I have specifically stated, ensure that satisfactory chimney performance may be obtained.

What I therefore claim and desire to secure by Letters Patent is:

1. A chimney cap for attachment to a chimney, said cap comprising a plate member to close the u pe end of id himn an u w i posed conduit member supported by said plate member and opening through said plate member centrally thereof, said conduit member being, throughout its length, of substantially lesser cross sectional area than the upper end of said chimney, and a cap part approximately of frustro-conic form supported by said plate member and housing said conduit member in spaced relation thereto, said cap part extending above the upper end of said conduit member and having an upwardly opening vent of approximately the same area as the upper end of said conduit, and said cap part also having a plurality of openings adjacent said plate member and disposed about its periphery to ensure the free flow of air therethrough.

2. A chimney cap for attachment to a chimney, said cap comprising a plate member to close the upper end of said chimney, a conduit member centrally supported by said plate and opening therethrough with its upper end is disposed a substantial distance above said plate member, said conduit member being, throughout gits length, of substantially lesser cross sectional area than the upper end of said chimney, and a cap part approximately of frusto-conic form supported by said plate member and housing said conduit member in spaced relation thereto, said cap part including inner and outer metal walls and thermal insulation therebetween extending above the upper end of said conduit member and having an upwardly opening vent of approximately the same area as the upper end of said conduit, and said cap part also having a plurality of openings adjacent said plate member and disposed about its periphery to ensure the free flow of air therethrough.

3. In a chimney cap for attachment to a chimney, a plate member to close the upper end of said chimney, an upwardly disposed conduit member supported by and opening through said plate member centrally thereof, said member being, throughout its length of substantially lesser cross sectional area than the upper end of said chimney, and a cap part supported by said plate member and housing said conduit member in spaced inwardly tapering relation thereto, said cap part extending above the upper end of said conduit member and having an upwardly opening vent of approximately the same area as the upper end of said conduit, said cap part including inner and outer metal walls both of frustroconic form but meeting at said vent and thermal insulation between said cap walls and said cap part also having a plurality of openings adjacent said plate member and disposed about its periphery to ensure the free flow of air therethrough.

4. A chimney cap for attachment to a chimney, said cap comprising a plate member to close the upper end of said chimney, an upwardly disposed conduit member supported by said late member and opening through said plate member centrally thereof, said conduit member being, throughout its length, of substantially lesser cross sectional area than the upper end of said chimney, and a cap part supported by one of said members and housing said conduit member in spaced relation thereto, said cap part extending above the upper end of said conduit member and being approximately of frusto-conic form and having an upwardly opening vent of approximately the same area as the upper end of said conduit, and said cap part also having a plurality of openings adjacent said plate member and disposed about its periphery to ensure the free flow of air therethrough.

HAROLD A. SABIN, JR.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 7,409 Bain Feb. 5, 1833 493,407 Lucas Mar. 14, 1893 1,412,334 Bernstein l Apr. 11, 1922 1,888,290 Rhinow Nov. 22, 1932 2,068,916 Heppenstall A Jan. 26, 1937 2,188,564 Berg Jan. 30, 1940 2,340,410 Chancellor Feb. 1, 1944 2,483,922 Messer Oct. 4, 1949 2,573,436 Gray Oct. 30, 1951 FOREIGN PATENTS Number Country Date 2,250 Great Britain AugQ 28, 1871 20,078 Great Britain 1908 23,921 Great Britain I 1911 107,461 Great Britain July 5, 1917 136,252 Great Britain Dec. 10, 1919 

